Jed made some good comments: Mike Carrell wrote:
delivered to the battery in 1/12 hour, at a rate of (75)(12) = 900 kW, which will vaporize the battery. Obviously if these batteries can charge 10 times faster than normal batteries, as advertised, they must be remarkably efficient so they do not produce much waste heat. MC: That doesn't follow. Fast charging batteries requires monitoring of the charge state so as not to over charge, with drastic effects on the batery chemistry. The Toshiba design, with management circuits, may allow faster charging, but you are still doing work against chemical and other losses. My lithium ion camera batteries take many hours on trickle charge, and about three hours with a fast charger, so 10% is 30 minutes, not five. In principle, it may be possible to dissipate the waste heat, but don't count on it. 900,000 watts is a lot of power. Realize that power will be delivered at 12 V intially, but more like 48 volts for advanced electric automobiles -- it's still 18,750 amps. Most of the 900 kW would convert directly into electric potential, and only about 90 kW converting to heat. That's pretty hot, but with a good radiator and exhaust fan it would not vaporize the battery or cause a fire. With a lead-acid battery, which is 70% efficient, it would produce 200 or 300 kW, which *would* cause a fire. MC: Even with Jed's optimistic number, that's 90 radiant bathroom heaters in your car. Designing the heat dissipation system for that is no easy task. MC: Think about this carefully, and multiply by 10 cars at a time. Ot think about it in a remote rural station on the road from nowhere to nowhere else. Ah, but imagine the rural station equipped with buffer battery of batteries (BBB). Let's say enough to charge 5 cars. This would smooth out the flow and allow a reasonably small main electric feed. A huge charging station on a major highway with 20 charge bay slots might require a BBB large enough to hold a charge for ~100 cars, and an electric power main large enough to recharge the BBB in 2 or 3 hours. It would not need power mains capable of charging all 20 slots simultaneously. MC: Ah so, but no matter how you sturcture it, it is a massive problem. Just as the expressway gas station has big storage tanks, fed by tanker trucks, one can postulate big battery piles. After a while, it begins to look like an electrified railway system. <snip> The Toshiba site describes hybrid engine applications: "The new battery can quickly store energy produced by locomotives and automobiles. This speedy and highly effective recharge characteristic of the battery will support CO2 reduction, as the battery can save and re-use energy that was simply wasted before." MC: It sounds good, and a valuable contribution to the transition to another energy structure. Mike Carrell
